The U.S. and South Korea conducted a big military exercise Saturday, storming a simulated North Korean beach defense as tensions on the Korean Peninsula continue to rise and Kim Jong Un threatens to wipe out his enemies.

The amphibious landing drills on South Korea’s east coast are part of eight weeks of exercises with the U.S., which the South has said are the largest ever. North Korea responded to the drills calling the exercises “nuclear war moves” and threatened to respond with attacks, according to Reuters.

Tensions between the North and South raged on this week as Seoul announced more sanctions on Pyongyang, which the North responded by firing short-range ballistic missiles into the sea as a show of defiance and vowing to “liquidate” all remaining South Korea assets at a former joint factory park.

The missile firing came a day after North Korea media printed photos of Kim posing next to what appeared to be a mock-up of a nuclear warhead. Also, South Korea lawmakers said that the number of North Korean cyberattacks on the South has doubled over the past month.

The U.S. Navy said about 55 American Marine aircraft and 30 U.S. and South Korean ships, including the USS Bonhomme Richard and USS Boxer, took part in Saturday's military drill on the beaches near Pohang.

“They will penetrate notional enemy beach defenses, establish a beach head, and rapidly transition forces and sustainment ashore," the U.S. military said in a statement before the exercise, according to Reuters.

North Korea said it was prepared to counter the U.S. and South Korean forces “with an ultra-precision blitzkrieg strike of the Korean style.”

North Korea also reported it has a missing submarine, two defense officials told Fox News Friday. One official said the submarine is a 70-foot Yono class “midget” submarine that is diesel powered and ahs a crew of two, with room for a squad of saboteurs.

Earlier this week, Kim ordered its military to improve its nuclear attack capability by conducting more missile tests. He also claimed his country had miniaturized nuclear warheads to mount on ballistic missiles, which could be launched at South Korea.

The Associated Press contributed to this report.

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